356 



BIOLOGY OF THE LABORATORY MOUSE 



their way into the urinary tubules, and the sexual cycle occurs in the 

 epithelial cells of the convoluted tubules. Sporogony stages are shown in 

 Fig. 138. The sporocysts pass down the tubules and escape with the urine. 

 Infection can be affected by the administration through the mouth of urine 

 from an infected mouse. 



According to Jaffe (22) the parasite may also be found in the capillary 

 endothelial cells of the lungs and spleen. He points out that "infiltrates" 

 found in the cells of the kidney and especially of the lungs "suggest path- 

 ogenic qualities." Cannarella explains the interstitial infiltration as the 

 result of mechanical action and alteration of materials bv A', muris. He 



Fig. 138. — Sporozony stages of KlossieUa muris within kidney cells. A, mother- 

 sporoblast (X1435); B, daughter-sporoblasts (X1590); C, spores (X870). {From 

 Smith and Johnson.) 



finds that occasionally the interstitial infiltration leads to a sclerosis of the 

 organ accompanied by the reduction of the functional parenchyma. The 

 minute specks mentioned above which are seen externally represent necro- 

 biotic changes in the cortex. J. M. Twort and C. C. Twort (39) state that 

 undoubtedly in most cases this organism is the cause of nephritis in the 

 mouse, and that they expect to find KlossieUa nephritis in at least 90 per 

 cent of their animals after they have reached the age of 1 2 months. This 

 was concluded after about 12,000 post-mortem examinations. Other 

 organs where they have found the parasite include the brain, suprarenal, 

 lung, thyroid, spleen, lymph glands, and pituitarv- . 



This organism represents an excellent example of a parasite which may 

 introduce confusing factors into an experiment. Cannarella well recognizes 

 this for he writes: "II est done indispensable que les rechercheurs et les 



